The study, by Fernando Moscoso del Prado Martín at UC-Santa Barbara,analyzed a large corpus (a million words) of telephone conversations from men and women of different ages in terms of lexical diversity, syntactic diversity, and disfluency.

Lexical or vocabulary diversity is related to the number of different words one uses. Syntactic diversity is related to the complexity of the grammatical structures you use. And disfluency refers to false starts, rephrasings, “ums” and “ahs,” etc.

Vocabulary

The researcher found that both men and women increase in lexical diversity as they age in a fairly linear fashion.

It’s not a new finding that older adults have larger vocabularies. The reason appears to be due in part to the cumulative amount of pleasure reading they’ve done. Stanovich and colleagues (1995) found that when you take into account reading habits and preferences, age is no longer a factor in vocabulary size. A twenty-year-old avid reader can have a vocabulary as large or larger than a eighty year old who doesn’t read for pleasure.

While the patterns for men and women were roughly the same for lexical diversity, there were stark differences in Martín’s data between sexes on syntax and disfluency as they age.

Grammar

The study found that “[w]omen use increasingly diverse syntactic structures at least up to their late fifties. However, from age 45 onward, men exhibit a decrease in the diversity of the syntactic structures they use” (p. 950).

Can reading also slow or counteract these declines?

Some evidence suggests that it can. Montag and MacDonald (2015) found that children and college students who read more used more passive relative clauses in their speech than those who didn’t read as much. Reading can have an impact on how we talk and the syntax we use, not just on our vocabulary.

Disfluency

Martín also found that unlike women, men have a dramatically “increased number of speech disfluencies” as they grow older, while women do not “deteriorate in terms of fluency through their lifespan” (p. 950).